Apparatus for the control of highway crossing signals



1933- A. G. WILLIAMSON 1,933,781

APPARATUS FOR THE CONTROL OF HIGHWAY CROSSING SIGNALS Filed June 27, 1930 5 1 61 H2 H4 H 62 a 12\ P1 17 "9 60 J65 7 f9! 0 if? 8 6.9

lg? 54 95 g I Thermal AR a; Relay EE 7" B 74 8 26 g5 86f I 5 51 ;82 Y B 4 0 17 :1 5 66 .95 wi 13' 1 Z 50 @71 B A INVENTOR A,G W/H1bmson BY V M ATTORNEY Patented Nov. 7, 1933 UNi'FEi) STATES APPARATUS FOR THE CONTROL OF HIGH- WAY CROSSING SIGNALS Arba G. Williamson, Carnegie, Pa assignor to The Union Switch &

Signal Company, Swissvale, Pa., a corporation of Pennsylvania Application June 27, 1930. Serial No. 464,205

29 Claims.

My invention relates to apparatus for the control of highway crossing signals, and has for an object the provision of means controlled by a train approaching a highway for starting the operation of the signal at substantially the same interval of time before the train reaches the highway regardless of the speed of the train.

In highway crossing signals, it is customary to provide that a'highway signal shall display a danger warning when the approaching train reaches a point at a fixed distance from the highway. With this fixed point located far enough away from the highway so that the warning signal is displayed for a sufficient length of time for a train traveling at a high rate of speed, then the warning signal is displayed so long for a slow moving train that the warning signal becomes irksome to those using the highway, with the result that the warning signal may be disregarded altogether.

In providing means to insure that the operation of the warning signal is substantiallyof the same interval or" time before the train reaches the highway, regardless of thespeed of the train, it becomes necessary to not only consider the case of a train traveling at a uniform rateof speed, but also to consider the case where the approaching train changes its speed as it approaches the highway. Furthermore, it is necessary to provide that when a train is making switching movements in the vicinity of the highway, there is not a continuous operation'of the warning signal; that is to say, the signalmust not indicate the approach of a train when no a train is about to cross the highway.

I will describe one form of apparatus embodying my invention, and will then point out thenovel features thereof in claims.

The accompanying drawing is a diagrammatic view showing one form of apparatus embodying my invention. 7

The reference characters R and R designate track rails over which trafiic normally .moves in a direction as indicated by the arrow and which are intersected by the highway H, shown at the right-hand end of the figure. At the intersection there is provided a highway signal S indicated on the drawing by the symbol com monly used in the art to designate an electric bell; it will be understood however, that any of of the common forms of highway signals can be used.

The rails R and R are divided by the usual insulated joints to form two track sections 1--2 and 2-3, which sections are traveled successively by the train as it approaches the highway and which are to' be approximately equal in length. The section 2-3 is divided into subsections 2-2 2 2 and 2 The section 1-2 is provided with a track circuit which includes a track battery 4 and a track relay H 'At the point 2 of the section 23, an insulated joint 5 is inserted in the rail R and a relay H is connected to the rail on opposite sides of the insulated joint 5. At the right-hand end of the sub-section 2 2 a battery 6 is connected across the rails, while at the left-hand end of the sub-section 2-2 a track relay H is connected to the rails. Current will therefore flow from the battery 6, down the rail R, through the relay H back through rail R around the insulated joint 5 by way of the coil of relay H and then to battery 6. With this section of track unoccupied, the'normal flow of current from the battery 6 is sufficient to energize the track relay H so that its armature contacts 7 and 8 are in the raised positions as shown in the figure, but thisnormal flow of current is not sufiicient to energize the relay H so as to lift its armature contacts 9 and 10. With a train occupying the sub-section 22 so as to shunt the resistance of the relay H then the current flowing from battery 6 is materiallyincreased and with this increased flow of current, the relay H is then sufiiciently energized so that its armature contacts 9 and 10 will be raised into engagement with the contacts 12 and 13, respectively. As soon as the train passes the point 2 the current will be shunted away from the relay H and its armature will drop. The sub-section 2 -3 is provided with a track circuit including a battery 14 and a relay I-I. While as stated above, the'sections 12 and 2,3 are to be approximately equal in length, the subsections 22 2= ---2 and 2 3 are not' equal and may be varied to suit conditions.

The highway signal S is under the direct control of a line relay L, and is operatedby a circuit consisting of the elements: battery terminal B, back contact 15 of relay L, armature 16 in its down position, wire 17, coil of the signal S, to battery terminal C. The relay L is under the joint ontrol of the track relays H H Hfla time measuring device designated as a whole by the reference character A, and a device designated TH.

The time, measuring device A consists of a shaft 18, shown diagrammatically as a dotted line, on which are rigidly mounted the three cams C C C and a disc 19. The device also comprises a dynamotor G-lVl mounted on a shaft 11 which carries a disc 20 in frictional engagement with the disc 19, so that operation or" the motor M causes operation of the shaft 18. It will be understood that other forms of gear reduction may be employed between the shafts 11 and 18. The complete movement of the cam shaft 18 is assumed to be 180, and the gear reduction is to be such that it requires approximately 126 seconds operation of the motor M to make this 180 movement of the shaft 18. The normal position of the shaft 18 with cams C C and C is that shown in thefigure, while.

the position 186 counterclockwise from the position shown, is the reverse position.

The cam C operates the contacts 23 and 29, and with the cam C in the position as shown so that the notch 44 comes opposite the operating arm of contact 29, the arm 45 is pulled to the right by the action of the spring 46 to thereby open the contact 29. As the cam C starts to rotate in the counter-clockwise direction from its full normal position, the arm 45 is at once "forced to the left by the cam to close contact 29. With the cam 0 rotated 180, that is, to the full reverse position, and the notch 44 opposite the arm 47 of the contact 23, the spring 48 will pull arm 4'7 to the left to open contact 23.

The cam C operates the contacts 51 and 53, and as the cam is moved away from its normal position, the spring 56 will at once pull the arm 49 to the left, to open the contact 51. The C is so positioned that after 30 movement, that is, twenty seconds operation of the motor M, it forces the arm 52 to the left against the action of the spring 92, to close the contact 53, and contact 53 then remains closed for the remaining portion of the movement. The cam C operates the contact and is so positioned as to close the contact from about 5 from the normal position to about 20 from normal. In this description, I shall referto the movement from the normal position to the reverse position of the device A as a forward movement and the movement from the reverse position to the normal position as a backward movement.

The armatureof the motor M of the dynamotor is supplied with current from a battery 21 along the wire 22, contact 23 of the cam C wire 24, front contact 25 of a relay AR to be described later, armature 26, wire 27, motor M, and wire 28 back to battery, or it may be supplied by current from the battery 21 along wire 22, contact 28 of cam C wire 36, back contact 31of relay AR, armature 26 in its down position and as before traced. The field winding 36 of the motor M is supplied with current fromthe battery 21 along Wire 22, contact 23, wire 24, wire 32, front contact 33, armature 34, wire 35, field 36, wire 3'], armature 38, front contact 39 and wires 46 and 28 to battery 21, or field winding 36 may be sup: plied with current from battery 21 along wire 22, contact 29, wire 30, contact 41, armature 38, wire 37, field 36, wire 35, armature 34, back contact 42 and wires 46 and 28 to battery.

Thus, it will be seen that with the relay AR. energized and the c'ontact23 close-:1, current is supplied to both the armature and the field winding of the motor M and that with the relay AR deenergized and the contact 29 closed, the current is likewise supplied to both armature field of the motor M, but, in this latter case, the direction of current through the field 36 is reversed to that in the first case. Thus, with the relay AR energized and contact 212 closed, the

motor rotates in a direction to cause the shaft 18 and the cams to be moved through the for ward movement, while with relay AR deenergizedand contact 29 closed, the rotation of the motor M is such as to produce the backward movement of the shaft and cams.

The relay AB is normally deenergized and is energized by a circuit from battery B along wire 56, contact 51 closed only when cam C is in normal position, wire 57, coil of relay AR, wire 58, back contact 59, armature in its down position, wire 61, contact 62 of relay H2, armature 'i', and to common battery. is provided with a stick circuit which passes from battery terminal B, through wire 63, contact 64 of relay AR, winding of the same relay, and then as before to battery terminal C. With the track section 12 occupied so as to shunt the relay H and the timing device A, occupying its full normal position, the relay AB is energized and once energized it will be retained energized through its stick circuit until the relay H is deenergized or therelay H again reenergized.

The generator end G of the dynamotor GM is designed to deliver the same voltage as that of the line battery (not shown) used with my invention and which is commonly taken as 10 volts, and the generator G is of sufiicient capacity so that it will deliver current to readily energize any relay that may also be energized by the line battery. A relay K is associated with the time measuring device A, the energizing circuit for which relay is from the positive terminalof the generator G along wire 65, contact 55, wire 66, coil of relay K, wire 6'7, back contact 68 of relay H armature 7, common wire, wire 69, armature '70 of the relay AR, back contact '71 and wire '72 to the negative terminal of generator G. Thus with the time measuring device A moving from the reverse position to its normal position so that the contact 55 is closed for a period and with the relay H shunted, the relay K will be energized by current from the generator G and the relay K will then be held energized by the stick circuit consisting of battery terminal B, wire '73, armature '74, front contact 75, coil of relay K, wire 6'7, contact 68, armature '7 and the common battery terminal. The relay TH is a thermal relay and may be one of any of the types well known in the art and it is designed to close its contact 76 a predetermined interval after its energizing circuit is closed, and in this description, it will be con sidered that the contact 76 is closed only after the relay TH has been energized for a period of twenty seconds. The energizing circuit for relay TH consists of battery terminal B, armature 9 of relay H contact 12, wire 77, relay TH, wire 78, armature 80 of a stick relay ST about to be referred to, back contact '79 and common battery. Associated with the relay TH is the stick relay ST, the energizing circuit of which consists of battery terminal B, contact 76 of relay TH, wire 81, coil of relay ST and the common battery. The stick circuit for this relay ST consists of generator G, wire 65, contact 53, wires and 84, contact 85, wire 86, coil of ST, common wire, wire 69, armature '70, contact '71 and wire '72 to generator G. In the event the relay K has been picked up in the manner above described then this stick circuit of ST is supplied with current from battery terminal 13, armature 82, contact 83, wire 84, contact 85, wire 86, relay ST and to common battery.

Normally the line relay L is energized by a The relay AR circuit from the battery terminal B along contact 87, armature 8 of relay H wire 89, armature of the relay H4, wire 91, coil of relay L, and to common battery. A second circuit for energizing the relay L consists .of generator G, wire 65, contact 53, wire 93, wire -84, wire 94, contact 13 of the relay H armature 10, wire 95,

"wire 89, armature 90, wire 91, coil of relay L,

.relay K, contact 83, wire 84and then by either the path through the contact 13 of relay H or by the path through the-contact 97 of the stick relay ST. 7 o

In describing the operation of my device, I shall assume that the highway signal S is to display a warning signal for a period of twenty seconds upon the approach of a train, and I shall assume that the sections 1-2 and 2-3 are each approximately 2640 feet in length, that the sub-section 22 is 880 feet in 1ength,and that the sub-section 2 3 is about 440 feet in length. Taking the maximum speed of a train to be ninety miles per hour, then as'such a train enters the section 12 and shunts the relay E the device A'will start on its forward movement. As soon as the device A leaves the full normal position, the contact 29 will be closed and at 'the end of twenty seconds, the contact 53 will be closed. However, if the train is traveling ninety miles per hour it will require only twenty seconds, to travel the entire section l2, and the train upon entering the section 23 shunts the relay H which deenergizes the relay AR thereby reversing the motor M so that the backward movement of device A is started, that is to say, the device A is reversed from its forward movement to its backward movement just before it has reached the point where the contact53 is closed. As the train shunts out the relay H it opens the circuit to the line relayLat the point 87 and as there is no other circuit closed whereby relay Lcan be energized; the highway signal S is rendered active to display a warning signal as soon as the train enters the section 23 and will remain active as the train travels this section. Inasmuch as the train is traveling at ninety miles an hour, it will travel the section -23 in twenty seconds, thus the highway signal .is displayed for twenty seconds before the hi hway is crossed by the train.

Let us now assume that the train is traveling at a speed of sixty miles per hour and thereby takes thirty seconds in traveling the sectionl-2. As before, the time measuring device A starts on its forward movement as soon as the train enters the section 1-2 and will continue in its forward movement until the time the train enters section 23 and shunts relay H which is thirty seconds. With device A making a thirty second forward movement, the contact 53 has been closed during the last ten seconds and it will remain thus closed for the firstten seconds of the backward movement. Thus as the train enters section 2-3 and shunts'relay H to open the circuit of relay L atcontact 87, current is supplied from the generatormG through the contact 53 to the wire89 leading to the relay L by way of the-contactil3 for a period of ten seconds. As the train is'traveling sixty miles 'anhour it will require thirty seconds to travel the section 2T3, and* therefore the signal S is displayed again for a'period'of twenty. J1 seconds before the train reaches the highway.

Let us nexttake the case of a slow moving trainhaving a speed-of filteen miles per hour and thereby requiringl20 seconds to travel the section l-2. ,The device A will thusmake a complete forward movement before it is reversed by the deenergizing' of relay AR and started on its backward movement, and the contact 53 will this time be retained closed fora period of one hundred seconds after the train enters section 2-3. While the ,train is: traveling from 2 to 2 the circuit from the generator G to, the relay L is through the front. contact 13 ,ofthe relay. H and'as soon as'the trainreaches the point 2 and shunts relay H current is supplied then to the relay L fromgenerator G by way of the contact 97 of the stick 'relay'ST, inasmuch as the train moving fifteen miles per hour requires forty seconds to travel from 2 to the point 2 and relay TH has ample time to close its con- .tact 76 thereby energizingythe stick relay ST.

The result is that current is supplied from generator G to the relay L for 'a period of one hundred seconds after the train has passed the point 2, and therefore the highway signal S will not become-active until just as the train enters the sub-section -2 -3, inasmuch .as I have taken sub-section .2 -3 asbeing 440 feet in length. Therefore the highway signal S in this case will be displayedfor a period of twenty seconds. I V

--In the above three cases,,I have assumed each time that the train traveling through the sections 1-2 and-2-3 did so at a uniform rate of speed. Let us now assumeacase where a train stops in the section l -2 so as to consume three or four minutes before it reaches the point 2 after it had passed the point 1. During this interval, the device A- has made a full forward movement to its reverse position and the motor M has been cut out at the point 23. Let us now say that this train advances and accelerates so that its speed bythe time it reaches the point 2 is forty miles per hour and thatit travels through the section 2-3 at this speed of forty miles per hour. Thedevice A havingto take 100 seconds of backward movement before the contact 53 is opened to deenergize the relay L, it is apparent that the device Awould. supply curre'ntto relay L all the time the train isftraveling the section 2 ,-3 and thus the highway signal S would never be rendered active to display a- -warning signal except as the train occupies 29-3, However, the train in traveling the sub-section 2-2, will do so in about 15 seconds and therefore: reach 2* before the thermal relay TH has had time'to close its contact '76.and thus as soon as the train shunts the relay H the relay L will become deenergized and thus the warning signal will become active. In this case we have assumed that the train requires thirty seconds" to travel the distance from 2 to 3, and the result is that the signal S will be displayed, in this case, for a period of thirty seconds. In other words, if a train is delayed in the section 1+2 and thenaccelerates to some higher'ra'te of j speed in'the' section 23, the warning signal 'S is rendered active as soon as the train'reaches the point 2 150 with the resultthat ample warning will be given by the signal S. i

Again let ,us assume that a train enters the section 2-3 and stops to fmake switching movements in the sub-section 22**. As soon as the device A has again returned to its normal position, the relay K will be energized. from generator G through the contact 55 and relay K once up will be retained up through its own stick circuit even after the motor M has been cut out and generator 6 ceases to deliver cur rent. With the relay K energized and contact 83 closed, the relay L is supplied with current from battery through the contact 83, as long as the train occupies either the sub-section 22 or 2 --2 When the train advances and enters the sub-section 2 3, the highway signal S will then become active to display a warning signal.

Although I have herein shown and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, means for starting the operation of said signal at substantially the same interval of time before a train reaches the intersection regardless of the speed of the train, and other means to insure the operation of said signal' for at least an equal interval of time notwithstanding a change in the speed of the train as it approaches said intersection.

2. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a first time measuring device for starting the operation of said signal at substantially the same interval of time before a train reaches the intersection regardless of the speed of the train, and a second time measuring device to insure the operation of said signal for a period at least equal to said interval of time notwithstanding a change in the speed of the train as it-approaches said intersection. t

3. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a first time measuring device set into operation when a. train approaches the intersection, circuit means controlled by said device for starting the operation of said signal at substantially the same interval of time before a train reaches the intersection regardless of the speed of the train, a second time measuring device also rendered active by a train approaching the intersection, and means controlled jointly by said two timemeasuring devices to insure at least anequal interval of operation of said signal notwithstanding a change in the speed of the train as it approaches the intersection.

4. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a time measuring device, a first circuit means controlled by a train approaching said intersection to set into operation said time measuring device, a sec ond circuit means controlled by said time measuring device for starting the operation of said signal at substantially the same interval of time beforefa train reaches the intersection regardless of the speed of the train, and a timing means adapted to cooperate with said time measuring device to insure at least an equal interval of operation of said signal notwithstanding a change in the speed of the train as it approaches the intersection.

5. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a time measuring device having a member with a forward movement and a backward movement, and including a reversible motor to move said member through said forward and backward movements,

means operating when a train approaches the intersection to energize the motor in a direction to move said member through the forward movement when the train passes one fixed point and to energize the motor in a direction to move the member through the backward movement when the train reaches a second fixed point, and means for setting said signal into opera tion when said member reaches a given point in its backward movement.

6. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a time measuring device including a motor element, and a generator element, means to set the motor element into operation when a train approaches the intersection for operating the time measuring device and to'actuate the generator element,

and a circuit supplied with current from said generator element and controlled by said time measuring device for starting the operation of said signal at substantially the same interval of time before a train reaches the intersection,

regardless of the speed of the train.

reaches the intersection regardless of the speed of the train.

8. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a track circuit effective to start the operation of said signal uponthe approach of a train, a time measuring device having a normal and a reverse position, a motor element set into operation as a train passes one fixed point as it approaches the intersection for operating the time measuring device away from normal position towards the reverse position and then as the train reaches a second fixed point reversing and returning said device to the normal position, means to render the track circuit ineffective to continue the operation of said signal when a train occupies a certain portion of the stretch after the time measuring device has been returned to its normal position, and a circuit controlled jointly by the motor 1 element and the time measuring device to render relay for each track section, a highway crossing signal located at the intersection, a controlling circuit for said signal including a front contact of the track relay for the track section closer to the highway; a time measuring device including a generator element, a motor element for op--' erating said time measuring device and said generator, and a normally open circuit controller adapted to be closed at a given point'in the movement of the device; a circuit for controlling the operation of the motor element jointly controlled by the track relay 'of each of the'track sections, and a shunt for said signal controlling circuit around said relay contact and including said circuit controller and said generator.

10. In combination, a stretch of railway track intersected by a'highway anddivided into a first and a second track section on one side of thehighway, a track relay for each track section, a highway crossing signal locatedat the intersection, a controlling circuit for said signal including a front contact of the track'relay of C the second track section; a time measuring device having a forward and a backward movement, and which device includes a generator and a motor for operating said time measuring device and adapted whenrunningfin a normal direction to give a forward movement of said time measuring device and, when running in the reverse direction to give a backward movement of said device; a circuit'means arrangedflto effect the normal direction of running of the motor when the relay of the first trackjsection is down and the relay of thesecond section is up and to effect the reverse direction .of running of said motor when either the trackrelay oi the first section is up or the relay of the second section is down, a normally open circuit controller operated by said time measuring device and adapted to be closed at a givenpoint in the forward movement and retained closed until the same point is reached in the backward movement, and a shunt for said signal controlling circuit around said relay contact and including said circuit controller and the saidgeneratorQ 11.In combination, a stretch of railway tracl; intersected by a highway divided into two track sections, a predetermined fixed intermediate point located in the track section closer to the highway, a time measuring device set into operation as a train enters the track section more remote from the highway, a highway crossing signal located at the intersection adapted to be set into operation as a train enters the track sec-, tion closer to the highway, means controlled by the time measuring device to hold in abeyance the operation of the signal for an interval varying inversely as the speed of the train, and a device set into operation as the train enters the track section closer to the highway to cancel the control of the time measuring device over the signal when the'train passes'the said intermediate point in less than a predetermined time.

12. In combination, a stretch of railway track intersectedby a highway and divided into two track sections on one side of the highway, a highway crossing signal located at the intersection, a controlling means to start operation of said signal as a train enters the track section closer to the highway, a first device to render the j controlling means ineffective to start operation of the signal as the train'enters the track section closer to the highway for an interval vary- 1 ing inversely as the average speed through the section more remote from the highway, and a second device to determine the average speed of nal located'at the and said current generating naling circuit includingsaid circuit controllertheftrain as ittravels a given portion of the track section closerto'the highway and to cancel the control or the first device over the controlling means when the train has increased its speed iii-the section closer to the highway over its average speedin the section more remote from the measuring device and closed only when said device occupies its normal position, and a controlling circuit responsiveto a train approach ing the intersection'to set into operation'the" motor of said time measuring device to move said device awayfrom its normal position, and

said circuit' including said circuit controller and; 190' cifective only when said circuit controller is closed. 11

14. In combination, a stretch of railway track intersected by-a highway, a highwaycrossingsig na-l located at the intersection-"a track circuit responsive to the presenceofa train to set into operation said signal, a motor operated time measuring device having a normal position and adapted when moved a predetermined'amount positionto render the' away fronr saidnormal track circuit ineffective to setinto operationsaid signal, and means effective its normal position to position in response to-a train approachingthe intersection. V

15. Incombination, a stretch of railway track intersectedby ahighway, a highway crossing sigintersection, a track section locatedon one side of the highway,-a trackrelay w only upon the cone; dition thatsaid time measuring device occupies H set into operation the] motortc move thedevice away from said normal for said tracksection, a controlling circuit in cluding a front contact of the track relay'to" set'the signal into operationas a train enters the track section, a thermal relay energized, as a train approachesthe' intersection, and "means around the said front contact- 7 16. In combination, a time measuring device controlled ibythe thermal relay to close a shunt" including-a'circuit controller, a current generating element and a motor element adapted to actuate said circuit controller and arranged to be supplied With current from the generating-element during a predetermined time interval of the uring device. I

17.:In=combination, a stretcher railway track intersected by a highway, a highwaycrossing signal locatedat the intersection, means for element, said motor element, and" a sigoperation offs'aid time mea sf setting said signal into operation when a'train approaching the intersection reaches a fixed" point, means including a timing device for delaying the operation of the signal, and. 'means controlledby said timing device for cutting said delaying means out of serv failure of the timing device.

ice in the eve fipq l 18.In combination, a stretch of railway track? intersected by a highway, a highway crossing signal' for the intcrsection,"a member normaliso 1y occupying a given position, means for mov-- ing said member away from said given position during the time interval required for a train approaching said highway to traverse a fixed distance, means effective when the train has traversed said fixed distance to restore said member to its given position at a predetermined rate, means controlled by said member for starting the operationof said signal at the end of a variable time interval after the train has traversed such fixed distance, which time, interval depends upon the distance said member has been moved away from the given position, and means for starting the operation of said signal as soon as the train has traversed such fixed distance in the event of failure of said member to be returned to its given position at said predetermined rate.

19. In combination, a stretch of railway track intersected by a highway, a highway crossing signal for the intersection, means for setting said signal into operation when a train approaching the intersection reaches a fixed point, a timing device controlled by the speed i the train and normally operating at a predetermined rate for delaying the operation of the signal, and means for rendering said device ineffective to delay the operation of said signal in the event of failure of the device to operate at such predetermined rate.

20. In combination, a stretch of railway track intersected by a highway, a highway crossing signal for'the intersection, a timing device having a forward and a backward movement, means set into operation as a train passes one fixed point as it approaches the intersection for op-' erating the timing device in. its forwardmovement and for initiating the backward movement of said device when the train reaches a second fixed point, means governed by the backward movement of the timing device to determine the time of starting the operation of the sigrial, and means rendered effective by the first said means during its backward movement to at once start the operation of the signal in the event of a failure of the first said means to function. V

21. In combination, a stretch of, railway track intersected by a highway, a highway crossing signal located at the intersection to be exhibited as a train approaches the intersection, a time measuring means governed both by the speed of a train and by changes in the speed of the train asit approaches the intersection, and circuit means controlled by said time measuring means.

for establishing the exhibit of said signal.

22. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, traffic controlled means for causing the exhibit of said signal as a train approaches the intersection, time measuring means governed both by the speed of the train and by changes in the speed of the train as it approaches the intersection to influence the traflic controlled means and thereby determine the interval for exhibiting said signal.

23. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, means for causing the exhibit of said signal upon the approach of a train to the intersection, and means for governing the time of starting the exhibit of said signal influenced bychanges in the speed of the train as it approaches said intersection.

24; In combination, a stretch of railway track intersected by a highway, a highway crossing signal for the intersection, a member normally occupying a given position, means for moving said member away from said given position during the time interval required for a train approaching said highway to traverse a fixed distance, means effective when the train has traversed said fixed distance to restore said member. to its given, position at a predetermined rate, means controlled by said member for starting the operation of said signal at the end of a variable time interval after the train has traversed such fixed distance, which time interval depends upon the distance said member has been moved away from the given position, and means for starting the operation of said signal after the train has traversed such fixed distance in the event of failure of said member to be returned to its given position at said predetermined rate.

25. In combination, a stretch of railway track intersected by a highway, a highway crossing signal for the intersection, a timing device having a forward and a backward movement, means set into operation-as a train passes one fixed point as it approaches the intersection for operating the timing device in its forward movement and for initiating the backward movement of said device when the train reaches a second fixed point, means governed by the backward movement of the timing device to determine the time of starting the operation of the signal, and means rendered effective by the first said means 'during'its backward movement tostart the operation of the signal in the event of a failure of the first said means to function.

26. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a track circuit responsive to the presence of a train approaching said intersection to set said signal into operation, a slow acting device having a normal position and adapted when moved a predetermined amount away from said normal position to render the track circuit ineffective to set said signal into operation, actuating means for moving said slow acting device, and means responsive to a train approaching the intersection before it reaches said track circuit for setting said actuating means into operation if and only if said slow acting device occupies its normal position.

.27. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a first and a second track section traversed successively by a' train approaching said intersection, a track circuit including a track relay for each track section, controlling means governed by the track relay of the second track section for starting operation of said signal as a train enters said second section, a device having a normal position and arranged to actuate an operating contact when moved a predetermined amount away from said starting position, a normally deenergized' motor for moving said device, a normally deenergized operating relay; a circuit for said operatingrelay including a front contact of the track relay of the second section, a back contact of the track, relay of the first section and a contact closed only when said device is in its. normal position, .a circuitincluding a front contact of the operating relay to energize-said motor, and means including said operating contact anda contact. governed by said operating relay for rendering the track relay of the second section inefiective to cause said controlling means to set said signal into operation.

28. In combination, a stretch of railway track intersected by a highway, a highway crossing signal located at the intersection, a time measuring device including a motor element and a circuit controller element, means to set the motor element into operation when a train approaches the intersection to actuate the circuit controller element, a circuit governed by said circuit controller element for starting the operation of said signal at substantially the same interval before a train reaches the intersection regardless of the speed of the train, and a source of current for said circuit rendered available when and only when the motor element is in operation.

29. In combination, a stretch of railway track intersected by a highway, a highway crossing si nal located at the intersection, a time measuring device including a motor element and a circuit controller element, means to set the motor element into operation when a train approaches the intersection to actuate the circuit controller element, a circuit governed by said circuit controller element for starting the op- V when the motor element is in operation;

ARBA G. WILLIAMSON. 

